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Viticulture
Viticulture (from the Latin word for vine) is the science, production and study of grapes which deals with the series of events that occur in the vineyard. When the grapes are used for winemaking, it is also known as viniculture. It is a branch of the science of horticulture. While the native territory of Vitis vinifera, the common grape vine, is a band of area from Western Europe to the Persian shores of the Caspian Sea, the vine has demonstrated high levels of adaptability and will sometimes mutate to accommodate a new environment after its introduction. Because of this, viticulture can be found on every continent except Antarctica. Duties of the viticulturist include: monitoring and controlling pests and diseases, fertilizing, irrigation, canopy management, monitoring fruit development and characteristics, deciding when to harvest and vine pruning during the winter months. Viticulturists are often intimately involved with winemakers, because vineyard management and the resulting grape characteristics provide the basis from which winemaking can begin. History The history of viticulture is closely related to the history of wine with evidence of man cultivating wild grapes to make wine dating as far back as the Neolithic period. There is evidence that some of the earliest domestication of Vitis vinifera occurred in the area of the modern day country of Georgia. There is also evidence of grape domestication occurring Near East in the Early Bronze Age around 3200 BC. The earliest act of cultivation appears to have been the favoring of Hermaphroditic members of the Vitis vinifera species over the barren male vines and the female vines which were dependent on having a nearby male to pollinate. With the ability to pollinate itself, over time the hermaphroditic vines were able to sire offspring that was consistently hermaphroditic itself. At the end of the 5th century BC, the Greek historian Thucydides wrote: The vast majority of the world's wine producing regions are found between the temperate latitudes of 30° and 50° in each hemisphere. Within these bands, the annual mean temperatures are between 50 and 68 °F. The presence of large bodies of water and mountain ranges can have positive effects on the climate and vines. Nearby lakes and rivers can serve as protection for drastic temperature drops at night by releasing the heat that the water has stored during the day to warm the vines. The vine needs approximately 1300-1500 hours of sunshine during the growing season and around 27 in of rainfall throughout the year in order to produce grapes suitable for winemaking. In ideal circumstances, the vine will receive most of the rainfall during the winter and spring months: rain at harvesttime can create many hazards, such as fungal diseases and berry splitting. The optimum weather during the growing season is a long, warm summer that allows the grapes the opportunity to ripen fully and to develop a balance between the levels of acids and sugars in the grape. Topography, too, is important. Hillsides and slopes are preferred over flatter terrain: vines growing on a slope receive a greater strength of the sun rays with sunshine falling on an angle perpendicular to the hillside; in flatter terrain, the strength of the sunlight is diluted as it is spread out across a wider surface area. Additionally, a slope affords better drainage, obviating the possibility that the vine might sit in overly moist soil. In cooler regions of the northern hemisphere, south-facing slopes receive more hours of sunlight and are preferred; in warmer climes, north-facing slopes are preferred (in the southern hemisphere, these orientations are reversed). Hazards and powdery mildew on a grape leaf.]] There are many hazards that a viticulturist needs to be aware of when growing vines. These hazards can have an adverse effect on the wine produced from the grape or kill the vine itself. When the vine is flowering it is very susceptible to weather hazards such as strong winds and hail. Cold temperatures during this period can also bring the onset of millerandage which produces clusters with no seeds and varying sizes. Too much heat can have the opposite reaction and produce Coulure that causes grape clusters to either drop to the ground or not fully develop. Viticultural hazards include: *Downy mildew *Powdery mildew *Frost *Oidium *Phylloxera *Plant virus Green harvest A green harvest is the removal of immature grape bunches, typically for the purpose of decreasing yield. In French, it is known as a vendange verte. Green harvesting is a relatively modern practice most often used to produce fine wine. Removing the tiny, immature grapes while they are still green induces the vine to put all its energy into developing the remaining grapes. In theory this results in better ripening and the development of more numerous and mature flavour compounds. In the absence of a green harvest, a healthy, vigorous vine can produce dilute, unripe grapes. Many traditionally renowned regions have natural conditions that suppress excess vigor. Examples include the gravelly soil of Bordeaux, the often cool climate of Burgundy, and the meager rainfall of La Rioja, Spain. In these regions, the vine is prevented from producing too many grapes without human intervention. However, in regions with fertile soil, copious sunlight, and irrigation, the vine can generate huge quantities of characterless grapes. One solution is a green harvest. After fruit set, the quantity of grapes that will result from a vineyard can be estimated. Often the grower has a target yield in mind, measured in tons per acre or hectoliters per hectare. A portion of the grape bunches are cut off, to leave approximately the correct amount. In Europe, many appellations restrict the yield permitted from a given area, so there is even more incentive to perform green harvesting when presented with excess crop. Often the excess must be sold for a pittance and used for industrial alcohol production rather than wine. While the concept of thinning or sacrificing part of the grape crop, i.e. green harvesting, with the aim of improving the quality of the remaining grapes, predates modern critics, the practice has increased in recent times in vineyards found in California and areas where the grapes grow easily. Field blend grapes in Côtes de Duras France'']] A field blend is a wine that is produced from two or more different grape varieties interplanted in the same vineyard. In the days before precise varietal identification, let alone rigorous clonal selection, a vineyard might be planted by taking cuttings from another vineyard and therefore approximately copying its genetic makeup. This meant that one vine could be Zinfandel and the next Carignan. When making wine with little equipment to spare for separate vinification of different varieties, field blends allowed effortless, though inflexible, blending. Fermentation tanks are now cheap enough that the field blend is an anachronism, and almost all wines are assembled by blending from smaller, individual lots. However, in California some of the oldest (and lowest-yielding) Zinfandel comes from vineyards that are field-blended. Ridge Vineyards owns the Lytton Springs vineyards in Sonoma County, which were planted from 1900 to 1905 in what Ridge calls "a traditional field blend of about seventy percent Zinfandel, twenty percent Petite Sirah, and ten percent Grenache and Carignan." Gemischter Satz (Mixed set) is a wine term in German equivalent to a field blend, which means that grapes of different varieties are planted, harvested and vinified together. In older times, this was common, but the practice has almost stopped. It is, however, a speciality of Vienna. See also *Ampelography *Annual growth cycle of grapevines *Diurnal temperature variation *Global warming and wine *List of vineyard soil types *Oenology *Precision viticulture *Vine training systems *Winemaking References External links * LIVE - Low Input Viticulture and Enology, Sustainable Viticulture Certification * AJEV - American Journal of Enology and Viticulture * Grape Pest Management Guidelines (IPM) UC IPM Online Pest * SAFECROP - Proceedings of the 5th International Workshop on Grapevine Downy and Powdery Mildew * Viticulture and Enology at Washington State University * Guide to Grape Vines * Viticulture on www.extension.org * GrapeLook: remote sensing for viticulture Category:Viticulture Category:Wine Category:Horticulture Category:Plant science